Force sensors of the type described above are used for a variety of purposes and are sold, for example, under the name of Press Force Sensor.
Examples of such force sensors are described in U.S. Pat. No. 7,493,836, which is hereby incorporated herein by this reference for all purposes. The measuring sensors described therein as being state of the art consist of a commercially available force sensor clamped between a bolt and a nut wherein both the bolt and the nut bear central tap holes on the outer surfaces thereof for the attachment of work pieces. This embodiment requires a considerable constructional height.
As an improved embodiment with regard to constructional height, a device is described in the same document wherein the sensor is directly integrated into the bolt. For attachment to adjoining work pieces there is either provided a central throughbore, several smaller tap holes on the frontal outer surfaces of the bolt and the nut or a central bore with a ledge serving as an internal bearing surface for a screw head of a mounting screw that is passed through the bore. Although the embodiment with the integrated sensor has a lower constructional height, its overall costs are higher as compared to the embodiment with a separate sensor because conventional sensors cannot be used.
Force sensors of this type are used for the measurement of the forces applied by manually operated or pneumatic presses, for example. Since the stroke of such presses is not very high due to the nature of the system, the force sensors employed therein should not be higher than 50 mm for hand presses up to 60 kN, for example. It is also important that the mounting fixtures at both external end faces of the force sensor can be easily adapted to the specifications of the manufacturer of the presses.